Re: [PATCH net-next] x86: bpf_jit_comp: secure bpf jit against sprayingattacks

[Daniel Borkmann]

On 05/18/2013 04:37 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
>
> hpa bringed into my attention some security related issues
> with BPF JIT on x86.
>
> This patch makes sure the bpf generated code is marked read only,
> as other kernel text sections.
>
> It also splits the unused space (we vmalloc() and only use a fraction of
> the page) in two parts, so that the generated bpf code not starts at a
> known offset in the page, but a pseudo random one.
>
> Refs:
> http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html
>
> Reported-by: H. Peter Anvin <hpa@xxxxxxxxx>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>

Great work !

Probably other archs could later on follow-up with setting to read-only, too.

Reviewed-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
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